Modular humeral implant

ABSTRACT

Modular humeral implants and methods of use. A humeral implant can include a stem portion, a metaphyseal portion, a locking element, and an intermediate portion. The intermediate portion can include at least one spacer. Each spacer can include a proximal engagement feature, a distal engagement feature, a lumen extending longitudinally through the spacer, and a pin slidable within the lumen of the spacer. Distal movement of a locking element in the metaphyseal portion can translate the pin of each spacer to secure the metaphyseal portion, the intermediate portion, and the stem portion in a locked configuration.

BACKGROUND

Field

The present application relates to apparatuses and methods for humeralimplants and trial humeral implants.

Description of the Related Art

A typical anatomical shoulder joint replacement attempts to mimicanatomic conditions. For example, a humeral stem and a humeral headreplacement are attached to the humerus of the arm and replace thehumeral side of the arthritic shoulder joint. The humeral headreplacement can articulate with the native glenoid socket or with anopposing glenoid resurfacing device.

For more severe cases, the standard treatment is a reversereconstruction, which includes reversing the kinematics of the shoulderjoint. A reverse shoulder prosthesis can be provided by securing asemi-spherical device (sometimes called a glenosphere) to the glenoidand implanting a humeral stem with a cavity capable of receiving theglenosphere.

Before implanting the humeral implant, it may be desirable to trial thehumeral implant to determine an appropriate length of the stem,appropriate inclination angle of the articulating head, and/or size ofthe articulating head, or other characteristics of the implant. Thetrial humeral implant can be assembled and then inserted into thehumerus. Afterwards, the entire trial implant can be removed, and thedefinitive humeral implant can be chosen and implanted in the bone.

SUMMARY

Humeral implants utilize modular components that can be assembledutilizing different lengths and diameters of stems, spacers, andmetaphases. Some humeral implants are assembled by screwing thecomponents of the implant together and then driving a screw through theentire implant or separately securing each component to an adjacentcomponent.

Utilizing the same components as the definitive humeral implant andsupplying all the different sizes of spacers for trialing is expensiveand cumbersome, for example, because assembling the components anddriving the screw through each trial implant can be difficult. Thus,there is a need for definitive humeral implants and/or trial humeralimplants that reduce the number of components, reduce the number ofsteps for assembly, and/or make assembly easier.

Certain aspects of this disclosure are directed toward a humeralimplant, including a metaphyseal portion, an intermediate portion, and astem portion. The humeral implant can be assembled together by slidingeach portion of the implant in a transverse direction relative to alongitudinal axis of an adjacent portion and into engagement with theadjacent portion. For example, the metaphyseal portion can include aslot and the intermediate portion can include a protrusion (or viceversa). The protrusion of the intermediate portion can slide into theslot of the metaphyseal portion by sliding the intermediate portion in atransverse direction relative to the longitudinal axis of themetaphyseal portion. As another example, the intermediate portion caninclude a slot and the stem portion can include a protrusion (or viceversa). The protrusion of the stem portion can slide into the slot ofthe intermediate portion by sliding the stem portion in a transversedirection relative to the longitudinal axis of the intermediate portion.This sliding motion can be less cumbersome and faster than screwing theseparate components together.

In some configurations, the portions of the humeral implant can beconfigured to engage each other unilaterally (e.g., a first componentcan only engage a corresponding second component when the secondcomponent is in a single orientation/configuration or when the secondcomponent is introduced from a particular side). For example, themetaphyseal portion can be configured to only engage the intermediateportion by introducing the intermediate portion from a particular sideof the intermediate portion and moving the intermediate in a directiontransverse to a longitudinal axis of the metaphyseal portion. As anotherexample, the intermediate portion can be configured to only engage thestem portion by introducing the stem portion from a particular side ofthe stem portion and moving the stem portion in a direction transverseto a longitudinal axis of the stem portion. The direction in which themetaphyseal portion engages the intermediate portion may be the same asor different from the direction in which the intermediate portionengages the stem portion. Limiting the orientation of assembly may bedesirable to ensure each portion of the implant is properly oriented.

As described above, the intermediate portion can include at least onespacer. Each spacer can include a proximal engagement feature and adistal engagement feature. For configurations with multiple spacers(e.g., two, three, or more), the intermediate portion can be assembledby sliding each spacer in a transverse direction relative to alongitudinal axis of an adjacent spacer and into engagement with theadjacent spacer. For example, the distal engagement feature of a firstspacer can be a slot and a proximal engagement feature of a secondspacer can be a protrusion (or vice versa). The protrusion of the secondspacer can slide into the slot of the first spacer by sliding the secondspacer in a transverse direction relative to the longitudinal axis ofthe first spacer.

In some configurations, the spacers can be configured to engage eachother unilaterally. In other words, the first spacer can be configuredto only engage the second spacer by introducing the spacer from aparticular side of the second spacer and moving the second spacer in asingle direction transverse to a longitudinal axis of the first spacer.Limiting the orientation of assembly may be desirable to ensure eachspacer is properly oriented.

Certain aspects of the disclosure are directed toward a spacer for usein a medical implant. The spacer can include a body portion having afirst engagement feature and a second engagement feature. Each of thefirst engagement feature and the second engagement feature can beconfigured to engage other components of the medical implant. A lumencan extend longitudinally through the body portion. A pin can beslidable through the lumen of the body portion. At least a distalportion of the pin can include a smooth outer surface. The pin caninclude a flange portion configured to limit proximal and/or distalmovement of the pin. A spring can be positioned radially between the pinand the body portion.

Certain aspects of this disclosure are directed toward a method ofsecuring the portions of the humeral implant in a locked configuration.To accomplish this, the intermediate portion can include one or morespacers (e.g., one, two, three, or more). Each spacer can include a pinslidable within a lumen of the spacer. After the metaphyseal portion,the intermediate portion, and the stem portion have been assembled (asdescribed above or otherwise), distal movement of a locking element inthe metaphyseal portion can translate the pin of each spacer to securethe humeral implant in a locked configuration. This method of securementdecreases the total time necessary to secure the humeral implanttogether by not requiring a user to drive a screw through a substantiallength of the humeral implant or separately secure adjacent portions ofthe implant.

Any feature, structure, or step disclosed herein can be replaced with orcombined with any other feature, structure, or step disclosed herein, oromitted. Further, for purposes of summarizing the disclosure, certainaspects, advantages, and features of the inventions have been describedherein. It is to be understood that not necessarily any or all suchadvantages are achieved in accordance with any particular embodiment ofthe inventions disclosed herein. No individual aspects of thisdisclosure are essential or indispensable.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments are depicted in the accompanying drawings forillustrative purposes, and should in no way be interpreted as limitingthe scope of the embodiments. Furthermore, various features of differentdisclosed embodiments can be combined to form additional embodiments,which are part of this disclosure.

FIG. 1 illustrates a humeral implant implanted in a humerus.

FIG. 2A illustrates a perspective view of an embodiment of a humeralimplant including a single spacer.

FIG. 2B illustrates a perspective view of an embodiment of a humeralimplant including multiple spacers.

FIG. 3 illustrates an exploded view of the humeral implant shown in FIG.2A.

FIG. 4 illustrates a perspective view of an embodiment of a reversedmetaphyseal portion partially engaged with a spacer.

FIG. 5A illustrates a partial cross-section of the humeral implant shownin FIG. 2A taken through line 5A,5B-5A,5B with the humeral implant in anunlocked configuration.

FIG. 5B illustrates a partial cross-section of the humeral implant shownin FIG. 2A taken through line 5A,5B-5A,5B with the humeral implant in alocked configuration.

FIG. 6 illustrates a partial cross-section of the humeral implant shownin FIG. 2A taken through line 6-6 with the humeral implant in a lockedconfiguration.

FIG. 7A illustrates a perspective view of a reversed metaphysealportion.

FIG. 7B illustrates an alternate perspective view of the reversedmetaphyseal portion shown in FIG. 7A.

FIG. 7C illustrates a cross-section of the reversed metaphyseal portionshown in FIG. 7A.

FIG. 8A illustrates a perspective view of an anatomic metaphysealportion.

FIG. 8B illustrates a cross-section of the anatomic metaphyseal portionshown in FIG. 8A.

FIG. 9A illustrates a perspective view of a spacer.

FIG. 9B illustrates a cross-section of the spacer shown in FIG. 9A.

FIG. 10 illustrates a perspective view of a stem portion.

FIG. 11 illustrates an exploded view of an alternate embodiment of ahumeral implant.

DETAILED DESCRIPTION

Humeral implants can be monolithic structures or include modularcomponents. In either case, it may be desirable to create atemporary/trial implant to help determine the appropriate dimensions fora permanent implant. For example, the trial implant can include anarticular body, a metaphyseal portion, one or more spacers, and/or astem portion. The stem portion provides a platform for the metaphysealportion, which can be adapted to receive an anatomic or a reversedarticular body. The spacers can be utilized to adjust a length of theimplant.

Humeral Implants

FIG. 1 illustrates a humeral implant 2, and more specifically, a reversehumeral implant implanted/positioned in a humerus H. A reversedmetaphyseal portion 6 of the implant 2 is positioned within the humerusand can be configured to receive an articular component configured tointerface with an opposing glenoid component. Although, depending on theneeds of the patient, the humeral implant 2 may include an anatomicmetaphyseal portion (see FIGS. 8A and 8B).

FIG. 2A illustrates the humeral implant 2 including the metaphysealportion 6, an intermediate portion 10, and a stem portion 14. Asillustrated, the intermediate portion is positioned between themetaphyseal portion 6 and the stem portion 14. Depending on the desiredlength of the implant 2, the intermediate portion 10 can include one ormore spacers 18 (e.g., one, two, three, or more). In one non-limitingexample, a shorter length implant 2 may utilize one spacer 18 (see FIG.2A), whereas a longer length implant (see FIG. 2B) may utilize two ormore spacers 18. When implanted, the intermediate portion 10 and thestem portion 14 can be inserted into the humerus H and at least aportion of the metaphyseal portion 6 can remain exterior to a resectedportion of the humerus H (see FIG. 1).

As shown in FIG. 3, the metaphyseal portion 6 can include a metaphysealengagement feature 22. The metaphyseal engagement feature 22 can beconfigured to engage a proximal engagement feature 26 of the spacer 18.For example, as shown in FIG. 3, the metaphyseal engagement feature 22can be a slot, and the proximal engagement feature 26 of the spacer 18can be a protrusion. Although in other examples, the metaphysealengagement feature 22 can be a protrusion, and the proximal engagementfeature 26 of the spacer 18 can be a slot. More generally, one of themetaphyseal engagement feature 22 and the proximal engagement feature 26of the spacer 18 can be a slot, and the other of the metaphysealengagement feature 22 and the proximal engagement feature 26 of thespacer 18 can be a protrusion. Use of slots or similar structures (e.g.,recesses, channels, or otherwise) can eliminate rotation betweenadjacent components when assembled together.

A distal engagement feature 30 of the spacer 18 can be configured toengage a stem engagement feature 34 of the stem portion 14.Additionally, the distal engagement feature 30 can be configured toengage a proximal engagement feature 26 of another spacer (see FIG. 2Band later description). For example, one of the stem engagement feature34 and the distal engagement feature 30 of the spacer 18 can be a slot,and the other of the stem engagement feature 34 and the distalengagement feature 30 of the spacer 18 can be a protrusion. As shown inFIG. 3, the stem engagement feature 34 can be a protrusion, and thedistal engagement feature 30 of the spacer 18 can be a slot. Although inother examples, the stem engagement feature 34 can be a slot, and thedistal engagement feature 30 of the spacer 18 can be a protrusion.

As shown in FIG. 3, the engagement features can be T-shaped slots orT-shaped protrusions. More particularly, the T-shaped protrusion isshaped to be slidably received by the T-shaped slot. However, in otherembodiments, the protrusions and slots may be dovetailed, spherical,triangular, or otherwise shaped to facilitate engagement in a transversedirection. The shapes of the engagement features need not be the samealong a length of the implant 2, however the engagement features areprovided complementary in shape. For example, the metaphyseal engagementfeature 22 and the proximal engagement feature 26 can be T-shaped, whilethe distal engagement feature 30 and the stem engagement feature 34 canbe rounded. As will be later described, the slots can be structured toonly receive the protrusions when the protrusions are introduced from aparticular side of the protrusions.

The engagement features of each of the metaphyseal portion 6, theintermediate portion 10, and the stem portion 14 of the humeral implant2 can be shaped such that adjacent portions can be assembled by moving(e.g., translating or sliding) one portion in a transverse directionrelative to a longitudinal axis of the adjacent portion. For example, asshown in FIG. 4, the metaphyseal engagement feature 22 can be shaped toengage the proximal engagement feature 26 of the spacer 18 by slidingthe spacer 18 in a transverse direction relative to a longitudinal axisL of the metaphyseal portion 6. Although not shown, the distalengagement feature 30 of the spacer 18 can be shaped to engage the stemengagement feature 34 by sliding the stem portion 14 in a transversedirection relative to a longitudinal axis “L” of the spacer 18. Thissliding motion can be performed in a single motion.

The metaphyseal portion 6, the intermediate portion 10, and the stemportion 14 of the humeral implant 2 can be configured to engage eachother unilaterally (e.g., a first component can only engage acorresponding second component when the second component is in a singleorientation/configuration or when the second component is introducedfrom a particular side). Limiting the direction in which the componentscan be assembled may be desirable to ensure each component of theimplant 2 is properly oriented. For example, the metaphyseal engagementfeature 22 can be configured to only engage the proximal engagementfeature 26 of the spacer 18 by introducing the proximal engagementfeature 26 into the metaphyseal engagement feature 22 from a particularside of the proximal engagement feature 26, e.g., from the side of theproximal engagement feature 26 including the groove 20 (as describedfurther below). The spacer 18 can be moved in a single directiontransverse to a longitudinal axis of the metaphyseal portion 6 to fullyengage the metaphyseal portion 6 and the spacer 18. To disengage thespacer 18 from the metaphyseal portion 6, the spacer 18 must beretracted in a direction that is opposite from the direction in whichthe spacer 18 was introduced. Although, other structures can be imaginedin which the spacer 18 can be disengaged from the metaphyseal portion 6by continuing to move the spacer 18 in a direction that is the same asthe direction in which the spacer 18 was introduced.

As another example, the distal engagement feature 30 of the spacer 18can be configured to only engage the stem engagement feature 34 byintroducing the stem engagement feature 34 into the distal engagementfeature 30 from a particular side of the stem engagement feature 34,e.g., from the side of the stem engagement feature 34 including thegroove 36. The stem portion 14 can be moved in a single directiontransverse to a longitudinal axis of the stem portion 14. To disengagethe stem portion 14 from the spacer 18, the stem portion 14 must beretracted in a direction that is opposite the direction in which thestem portion 14 was introduced. Although, other structures can beimagined in which the stem portion 14 can be disengaged from the spacer18 by continuing to move the stem portion 14 in a direction that is thesame as the direction in which the stem portion 14 was introduced.

As shown in FIG. 4, the proximal engagement feature 26 of the spacer 18can include a groove 20 (or notch, recess, channel, or otherwise)extending partially across a proximal face 23 of the proximal engagementfeature 26. The groove 20 can extend from a first lateral edge 25 a ofthe proximal face 23 (see FIG. 3) to the lumen 56 (not shown). Thegroove 20 can facilitate proper orientation between the spacer 18 andthe metaphyseal portion 6.

As shown in FIG. 5A, at rest, a distal end 38 a of the locking element38 can extend into the metaphyseal engagement feature 22. The distal end38 a of the locking element 38 can prevent the proximal engagementfeature 26 from engaging the metaphyseal engagement feature 22 unlessthe proximal engagement feature 26 is introduced from the first lateraledge 25 a having the groove 20 (see FIG. 4). The groove 20 can beconfigured to guide the distal end 38 a of the locking element 38 towardthe lumen 56 (not shown). If the proximal engagement feature 26 isintroduced into metaphyseal engagement feature 22 from the oppositesecond lateral edge 25 b of the proximal engagement feature 26 (seeFIGS. 3 and 4), the proximal engagement feature 26 will not be able toengage the metaphyseal engagement feature 22.

Similarly, as shown in FIG. 3, the stem engagement feature 34 caninclude a groove 36 or notch, recess, channel, or otherwise) extendingpartially across a proximal face 32 of the stem engagement feature 34.The groove 36 can extend from a first lateral edge 37 a of the proximalface 32 (see FIG. 3) to the lumen 60 (not shown).

A shown in FIG. 5A, at rest, a distal end 42 b of the pin 42 can extendinto the stem engagement feature 34. The distal end 42 b of the pin 42can prevent the distal engagement feature 30 from engaging the stemengagement feature 34 unless stem engagement feature 34 is introducedfrom the first lateral edge 37 a having the groove 36. If the stemengagement feature 34 is introduced into the distal engagement feature30 from the opposite second lateral edge 37 b of the stem engagementfeature 34 (see FIG. 3), the stem engagement feature 34 will not be ableto engage the distal engagement feature 30.

After the metaphyseal portion 6, the intermediate portion 10, and thestem portion 14 have been assembled (as described above or otherwise),the humeral implant 2 can include a locking assembly to transition theimplant 2 from an unlocked configuration (see FIG. 5A) and a lockedconfiguration (see FIG. 5B). In the locked configuration, themetaphyseal portion 6, the intermediate portion 10, and the stem portion14 can be longitudinally and transversely locked relative to each other.

When the implant 2 is assembled, a lumen 86 of the metaphyseal portion 6can be longitudinally aligned with a lumen 56 of the spacer 18 and therecess 60 of the stem portion 14 (see FIGS. 5A and 5B). Since the lumens56, 86 are aligned, a locking element 38 in the metaphyseal portion 6can be longitudinally aligned with a pin 42 in the spacer 18. Thelocking element 38 can be sufficiently long to contact a proximal end 42a of pin 42, so the locking element 38 and the pin 42 can form acontinuous rod extending through the implant 2. When the implant 2 isassembled, the locking element 38 only partially extends through theadjacent spacer 18. As shown in FIG. 5B, in the locked configuration, adistal end 38 a of the locking element 38 may be positioned in a portionof the lumen 56 extending through the proximal engagement feature 26 ofthe spacer 18.

Distal movement of the locking element 38 (e.g., by pushing, rotating,or otherwise moving) can translate the pin 42 longitudinally to securethe humeral implant 2 in a locked configuration (see FIG. 5B). In thelocked configuration, at least a distal portion of the locking element38 can extend into a lumen 56 of the spacer 18 such that the lockingelement 38 traverses the intermediate portion 10 and the metaphysealportion 6. At least a distal portion of the pin 42 can be positioned ina recess 60 of the stem portion 6 such that the pin 42 traverses theintermediate portion 10 and the stem portion 6.

As shown in FIGS. 5A and 5B, the locking element 38 can include aproximal portion 40 and a distal portion 44. The proximal portion 40 ofthe locking element 38 can threadably engage the metaphyseal portion 6.The distal portion 44 of the locking element can have a smooth exteriorsurface. Although in other embodiments, the distal portion 44 can bethreaded and the proximal portion 40 can be smooth, the locking element38 can be threaded along an entire length of the locking element 38, orthe locking element 38 can be smooth along an entire length of thelocking element.

The locking element 38 can include a recess 50 in at least the proximalportion 40 of the locking element 38. The recess 50 can be configured toreceive a tool (e.g., screw driver, hex-shaped tool, or otherwise) thatcan rotate or rotatably engage the locking element 38. Rotation of thelocking element 38 can translate the locking element 38 distally (seeFIG. 5B) and proximally (see FIG. 5A). In some configurations, less thanabout four rotations of the locking element (e.g., less than aboutthree, less than about two, or otherwise) can move the implant 2 betweenthe locked configuration and the unlocked configuration. In someconfigurations, a single rotation (e.g., 360 degrees) of the lockingelement 38 can move the implant 2 between the locked configuration andthe unlocked configuration. A fewer number of rotations may bebeneficial to decrease the amount of work and time necessary to assembleand disassemble the implant 2.

To unlock the implant 2, the locking element 38 can be moved proximally(e.g., by pushing, rotating, or otherwise moving) to permit the pin 42to translate proximally and release the implant 2 from the lockedconfiguration to the unlocked configuration (see FIG. 5A). This methodof securement and unsecurement decreases the total time necessary tosecure the humeral implant together by not requiring a user to drive ascrew through a substantial length of the humeral implant or separatelysecure adjacent portions of the implant.

To facilitate release of the implant 2 from the locked configuration,the stem portion 6 can include a channel 64 extending from an outersurface of the stem portion 14 to a distal end of the recess 60 (seeFIG. 6). The channel 64 can be shaped to receive an elongate structure(e.g., a pin, guidewire, screw driver, or otherwise) (not shown). Theelongate structure can push a distal end of the pin 42 proximally torelease the implant from the locked configuration.

To disassemble the implant 2, each component must be retracted in adirection opposite from the direction in which that component wasintroduced. Since the groove 20 only extends partially across a proximalface 23 of the proximal engagement feature 26, the distal end 38 a ofthe locking element 38 is prevented from moving beyond the lumen 26 andtoward the second lateral edge 25 b of the proximal engagement feature26. Similarly, since the groove 36 only extends partially across aproximal face 32 of the stem engagement feature 34, the distal end 42 bof the pin 42 is prevented from moving beyond the lumen 60 and towardthe second lateral edge 37 b of the stem engagement feature 34.

Turning to FIGS. 7A-7C, the metaphyseal portion 6 can be a reversedmetaphyseal portion. The metaphyseal portion 6 can be configured toreceive an articular component having a cavity configured to interfacewith a glenosphere. An exterior surface of the metaphyseal portion 6 caninclude a number of scalloped features 144 configured to interface withthe bone. A proximal-facing surface 90 can be at an incline relative toa longitudinal axis L of the metaphyseal portion 6 (see FIG. 7A). Adistal surface 110 of the metaphyseal portion 6 can include teeth (seeFIG. 7B), which can interface with a proximal face of the spacer 18 evenif the spacer 18 does not have the corresponding proximal engagementfeature 22. If a humeral stem of a previously implanted humeral implantis left in the bone, a metaphyseal portion 6 can interface with thehumeral stem using the teeth on the distal surface 110 of themetaphyseal portion 6, even if the humeral stem does not have theT-shaped or otherwise appropriately shaped engagement feature.

As shown in FIG. 7C, the metaphyseal portion 6 can include a first lumen82 and a second lumen 86. The first lumen 82 can be configured toreceive a corresponding engagement feature of the articular component.The first lumen 82 can extend at least partially through the metaphysealportion 6. The first lumen 82 can extend from a proximal opening at theproximal-facing surface 90 of the metaphyseal portion 6 and extendtoward the longitudinal axis L of the metaphyseal portion 6. An axis Aextending through first lumen 82 can be positioned at a non-zero anglerelative to the longitudinal axis L of the metaphyseal portion 6.

The second lumen 86 can extend entirely through the metaphyseal portion6 and along a longitudinal axis L of the metaphyseal portion 6 (see FIG.7C). The second lumen 86 can include a proximal opening and a distalopening. The proximal opening can be positioned at an angle relative tothe proximal-facing surface 90 and/or at least partially recessed fromthe proximal-facing surface 90. The distal opening can be positioned ata distal-facing surface 94 of the metaphyseal portion 6.

The second lumen 86 can include a first portion 98 and a second portion102 proximal to the first portion 98 (see FIG. 7C). A diameter of thesecond portion 102 can be greater than a diameter of the first portion98. The first portion 98 can be configured to receive the lockingelement 38 (see FIGS. 5A and 5B). At least a section of the firstportion 98 can be threaded to threadably engage the locking element 38.For example, a proximal section 106 of the first portion 98 can beconfigured to receive a threaded portion of the locking element 38. Thesecond lumen 86 can include a shoulder 108 on which the locking element38 can sit when the implant 2 is in the locked configuration (see FIG.7C). In other configurations, the entire first portion 98 can bethreaded, a distal section of the first portion 98 can be threaded, orthe entire first portion 98 can be smooth.

As shown in FIG. 7C, the metaphyseal engagement feature 22 can be aT-shaped slot. The T-shaped slot can include a first portion 100 and asecond portion 104. A width w₁ of the first portion 100 can be greaterthan a width w₂ of the second portion 104. The second portion 104 can bepositioned at an end of the metaphyseal engagement feature 22.

FIGS. 8A and 8B illustrate an anatomic metaphyseal portion 150 that canbe used during anatomic shoulder replacements. The anatomic metaphysealportion 150 can interface with the intermediate portion 10 and the stemportion 14 similar to the reverse metaphyseal portion 6.

Similar to the reverse metaphyseal portion 6, the anatomic metaphysealportion 150 can include scalloped features 154 on an exterior surface ofthe metaphyseal portion 150 and/or teeth on a distal surface 158 of themetaphyseal portion 150. The metaphyseal portion 150 can include ametaphyseal engagement feature 156 that can engage the proximalengagement feature 22 of the spacer 18.

The metaphyseal portion 150 can include a first lumen 166 and a secondlumen 170 (see FIG. 8B). The first lumen 166 can extend at leastpartially through the metaphyseal portion 150. The first lumen 166 canextend from a proximal opening at a proximal, inclined surface 186 ofthe metaphyseal portion 150 and extend toward the longitudinal axis L ofthe metaphyseal portion 150. The first lumen 166 can include a distalopening along the second lumen 170. An axis B extending through firstlumen 166 can be positioned at a non-zero angle relative to thelongitudinal axis L of the metaphyseal portion 150. A section 174 of thefirst lumen 166 can be threaded to threadably engage the articularcomponent.

The second lumen 170 can extend entirely through the metaphyseal portion150 and along a longitudinal axis L of the metaphyseal portion 150 (seeFIG. 8B). The second lumen 170 can include a proximal opening and adistal opening. The proximal opening can be positioned at aproximal-facing surface 190 of the metaphyseal portion 150. The distalopening can be positioned at a distal-facing surface 194 of themetaphyseal portion 150.

The second lumen 170 can include a first portion 178 and a secondportion 182 proximal to the first portion 178. A diameter of the secondportion 182 can be greater than a diameter of the first portion 178. Thefirst portion 178 can be configured to receive the locking element 38(see FIGS. 5A and 5B). At least a section of the first portion 178 canbe threaded to threadably engage the locking element 38. For example,the proximal section 198 of the first portion 178 can be configured toreceive a threaded portion of the locking element 38 (see FIGS. 5A and5B). In other configurations, the entire first portion 178 can bethreaded, a distal section of the first portion 178 can be threaded, orthe entire first portion 178 can be smooth.

FIGS. 9A and 9B illustrate the spacer 18. As described above, theproximal engagement feature 26 can be a T-shaped protrusion. TheT-shaped protrusion can include a first portion 66 and a second portion70. A width w₃ of the first portion 66 can be greater than a width w₄ ofthe second portion 70. The first portion 66 can form an end of thespacer 18. The distal engagement feature 30 can be a T-shaped slot. TheT-shaped slot can include a first portion 74 and a second portion 78. Awidth w₅ of the first portion 74 can be greater than a width w₆ of thesecond portion 78. The second portion 78 can be positioned at an end ofthe spacer 18. In other embodiments, the proximal engagement feature 26can be a slot and the distal engagement feature 30 can be a protrusion.

As shown in FIG. 9B, the body portion 52 can include an interior surfaceforming the lumen 56. The lumen 56 can include a proximal portion 58 anda distal portion 62. A diameter of the proximal portion 58 can be lessthan a diameter of the distal portion 62. The junction between theproximal portion 58 and the distal portion 62 can form a shoulder 54.The shoulder 54 can limit proximal movement of the pin 42. For example,the pin 42 can include a flange portion 68. A diameter of the flangeportion 68 can be greater than the diameter of the proximal portion 58such that movement of the pin 42 is limited.

The pin 42 can be slidable within the lumen 56 of the spacer 18. Asshown in FIG. 9B, the pin 42 can be smooth along an entire surface ofthe pin 42. However, in other configurations, a portion of the pin 42may be threaded to facilitate engagement.

A length of the pin 42 can be less than a length of the body portion 52.At rest, the pin 42 can be sufficiently long such that a proximal end 42a of the pin 42 is positioned in the proximal engagement feature 26 anda distal end 42 b of the pin 42 protrudes beyond a distal-facing surface76 of the spacer 18 (see FIGS. 9A and 9B). In the locked configuration,the pin 42 can be sufficiently long such that the proximal end of thepin 42 is positioned in the proximal engagement feature 26 and a distalend of the pin 42 can be positioned in the stem engagement feature 34 ora proximal engagement feature 26 of an adjacent spacer 18 (see FIG. 5B).

The spacer 18 can include a biasing element 46 (e.g., a spring) disposedradially between the pin 42 and the body portion 52 (see FIG. 9B). Thebiasing element 46 can be positioned in the distal portion 62 of thelumen. The biasing element 46 can bias the pin 42 in a proximaldirection to facilitate release of the humeral implant 2 from the lockedconfiguration. As the locking element 38 is moved in a proximaldirection, the biasing element 46 can facilitate movement of the pin 42in a proximal direction to transition the implant 2 from the lockedconfiguration (see FIG. 5B) to the unlocked configuration (see FIG. 5A).

The spacer 18 can include a feature to limit distal movement of the pin42 and/or spring 46. For example, the spacer 18 can include a stopper48. The stopper 48 can be annular and include an opening through whichat least a portion of the pin 42 can extend (see FIG. 3). The stopper 48can be positioned in a distal portion of the spacer 18, e.g., in thelumen 56 of the body portion 52 (see FIG. 9B) or at a distal end of thelumen 56. The stopper 48 can be secured to the body portion 52 (e.g.,welded, adhered, press-fit, or otherwise). However, in otherconfigurations, the lumen 56 can be shaped to limit both proximal anddistal movement of the pin 42, a stopper 48 can limit both proximal anddistal movement of the pin 42, or a stopper 48 can limit proximalmovement of the pin 42 and a shoulder 54 can limit distal movement ofthe pin 42.

As shown in FIG. 9A, the spacer 18 can include at least one opening 43along a lateral wall of the spacer 18. The one or more openings 43provide access to flush out fluid or debris that may be in the spacer18.

FIG. 10 illustrates the stem portion 14. The stem portion 14 can includean elongate body portion 16 and a stem engagement feature 34. The stemengagement feature 34 can be a T-shaped protrusion. The T-shapedprotrusion can include a first portion 33 and a second portion 35. Awidth w₇ of the first portion 33 can be greater than a width w₈ of thesecond portion 35. The first portion 33 can form an end of the stemengagement feature 34. In certain embodiments, the stem may not bestraight, but rather, curved along the longitudinal axis “L.”

With reference to FIG. 11, another illustrative embodiment of a humeralimplant 1002 is shown. The humeral implant 1002 resembles or isidentical to the humeral implant 2 discussed above in many respects.Accordingly, numerals used to identify features of the humeral implant 2are incremented by a factor of one thousand (1000) to identify likefeatures of the humeral implant 1002. Any component or step disclosed inany embodiment in this specification can be used in other embodiments.

For a definitive humeral implant, it may be desirable to be able tosecure together the metaphyseal portion 1006, the intermediate portion1010, and the stem portion 1014 of the implant 1002. As shown in FIG.11, the engagement features of the metaphyseal portion 1006, theintermediate portion 1010, and the stem portion 1014 can be threaded tothreadably engage each other. The metaphysis portion 1006 can threadablyengage a proximal engagement feature 1026 of the spacer 1018. The spacer1018 can threadably engage a stem engagement feature 1034 of the stemportion 1014.

To further secure the metaphyseal portion 1006, the intermediate portion1010, and the stem portion 1014 of the implant 1002 in a lockedconfiguration, the implant 1002 can have a similar locking system to thehumeral implant 2 in which distal movement of the locking member 1038traverses a pin 1042 longitudinally to secure the implant 1002 in alocked configuration.

It should be noted that implants of the present disclosure may beprovided with coatings on the surface thereof. More particularly,certain portions of the implants may include porous titanium coatings.Alternatively, or additionally biological coatings may be provided onthe implants to promote bone growth. Such coatings are within thepurview of those skilled in the art.

Humeral Implant with Multiple Spacers

As shown in FIG. 2B, the intermediate portion 10 can include a pluralityof spacers 18 a, 18 b (e.g., two, three, four, or more) to extend alength of the implant 2. To assemble an intermediate portion 10 withmultiple spacers 18 a, 18 b a proximal engagement feature of a firstspacer 18 a can be configured to engage a distal engagement feature of asecond, adjacent spacer, and so forth. For example, a proximalengagement feature of the first spacer 18 a can be configured to engagethe metaphyseal engagement feature, and a distal engagement feature ofthe second spacer 18 b can be configured to engage the stem engagementfeature 34. The distal engagement feature of the first spacer 18 a canbe configured to engage the proximal engagement feature of the secondspacer 18 b by sliding the second spacer 18 b in a transverse directionrelative to a longitudinal axis of the first spacer 18 a. When theintermediate portion 10 is assembled, the lumens of the spacers form asingle lumen extending longitudinally through the intermediate portion10.

In some configurations, the spacers 18 a, 18 b can be configured toengage each other unilaterally (e.g., a first component can only engagea corresponding second component when the second component is in asingle orientation/configuration or when the second component isintroduced from a particular side). As discussed above, the orientationof engagement between adjacent portions may be limited by structures inthe engagement features. For example, the proximal engagement featuresmay include structures (e.g., grooves, channels, recesses, or otherwise)that limit the orientation in which the proximal engagement features canbe introduced into corresponding engagement features. Limiting theorientation of assembly may be desirable to ensure each spacer isproperly oriented.

Although not shown, if the intermediate portion 10 includes multiplespacers 18 a, 18 b, distal movement of the locking element 38 cantranslate the pin of each spacer 18 a, 18 b to secure the humeralimplant 2 in the locked configuration. Distal movement of the lockingelement 38 can longitudinally translate each subsequent pin. The lockingelement 38 can translate the first pin of the first spacer 18 a distallyinto a lumen of a second, adjacent spacer 18 b. Distal movement of thefirst pin can translate a second pin in the second spacer, and so forth,until at least a distal portion of the pin of the distal-most spacer ispositioned in the recess 60 of the stem portion 14. In the lockedconfiguration, a distal end of the first pin contacts a proximal end ofthe second pin, and so forth such that the locking element 38 and thepins 42 form a continuous rod extending through the implant 2.

The spacers 18 may be offered in different lengths. By offering a rangeof standard spacer lengths surgeons can customize overall assemblylength. This can reduce the number of trials required. For illustrationpurposes only, a set of three trials having 1 cm, 2 cm, and 3 cm lengthscan be used to trial the following lengths: 1 cm, 2 cm, 3 cm, 4 cm, 5cm, 6 cm. In this example, three modular trials can be used to model thesame sizes as six monolithic trials. Using this reasoning, fewerexpensive trial stems and fewer expensive trial metaphyses need besupplied provided a sufficient number of less expensive trial spacersare provided in a trial kit.

Method of Use

A trial humeral implant can include any combination of featuresdescribed in connection with the humeral implants 2, 1002. In general, ametaphyseal portion 6,150, 1006, an intermediate portion 10,1010, and astem portion 14,1014 can be assembled together and then locked togetherusing the locking assembly described herein. Although the method belowis described in connection with the reversed metaphyseal portion 6, thesame method can be utilized for the anatomic metaphyseal portion 150.

The metaphyseal portion 6, the intermediate portion 10, and the stemportion 14 can be assembled together by sliding each portion in atransverse direction relative to a longitudinal axis of an adjacentportion. For example, the metaphyseal portion 6 and the intermediateportion 10 can be assembled by sliding the intermediate portion 10 in atransverse direction relative to a longitudinal axis of the metaphysealportion 6 until the metaphyseal engagement feature 22 engages a proximalengagement feature 26 of the intermediate portion 10. The intermediateportion 10 and the stem portion 14 can be assembled by sliding the stemportion 14 in a transverse direction relative to a longitudinal axis ofthe intermediate portion 10 until a distal engagement feature 30 of theintermediate portion 10 engages a stem engagement feature 34. If theintermediate portion 10 includes multiple spacers 18, the intermediateportion 10 can be assembled by sliding each spacer in a transversedirection relative to a longitudinal axis of an adjacent spacer and intoengagement with the adjacent spacer, until a proximal engagement featureof a first spacer engages a distal engagement feature of a secondspacer.

After the trial humeral implant 2 has been assembled, the humeralimplant 2 can be transitioned from an unlocked configuration (see FIG.5A) to a locked configuration (see FIG. 5B). Distal movement of thelocking element 38 can translate the pin 42 of each spacer 38 in alongitudinal direction until the humeral implant 2 is in the lockedconfiguration. As the locking element 38 and the pin(s) 42 movedistally, the locking element 38 is introduced into the spacer 18 suchthat the locking element 38 traverses the metaphyseal portion 6 and theintermediate portion 10, and the distal-most pin is introduced into therecess 60 of the stem portion such that the distal-most pin 42 traversesthe stem portion 14 and the intermediate portion 10.

The locking element 38 can be driven by pushing, rotating, or otherwisemoving the locking element 38 distally. As shown in FIGS. 5A and 5B, thelocking element 38 can threadably engage the metaphyseal portion 6(e.g., via right-handed or left-handed threads or other configurations).The locking assembly can be configured such that a single rotation(e.g., 360 degrees) of the locking element 38 transitions the humeralimplant 2 between the unlocked configuration and the lockedconfiguration. Although, the humeral implant 2 can be configured suchthat multiple rotations (e.g., two, three, or four) of the lockingelement 38 transition the humeral implant between the unlockedconfiguration and the locked configuration.

The assembled trial humeral implant 2 can be impacted into a resectedhumerus, leaving a portion of the metaphyseal portion 6 exterior to thebone (see FIG. 1). After determining the appropriate size of thearticular component, the entire trial implant 2 can be removed using anextractor.

Based on the position of the assembled trial as impacted into thehumerus, the dimensions of the definitive humeral implant can beselected. The definitive humeral implant can include any of the featuresof the humeral implant 2, 1002. If the definitive humeral implantincludes slots and protrusions, the definitive humeral implant can beassembled as described above in connection with the trial humeralimplant 2. If the definitive implant includes the connection features ofthe humeral implant 1002, the metaphyseal portion 1006, the intermediateportion 1010, and the stem portion 1014 can be screwed together. Inanother embodiment, the definitive humeral implant may be a monolithicstructure instead of an assembly of components. Afterward, the humeralimplant 1002 can be locked into a locked configuration by using themethod described above in connection with the trial implant. Then, thedefinitive humeral implant can be implanted in the bone.

Over time, it may become necessary to perform a revision procedure toconvert an anatomic metaphyseal portion 150 to a reversed metaphysealportion 6. In those cases, it may be possible to remove only theanatomic metaphyseal portion 150 and leave the humeral stem in the bone.The reversed metaphyseal portion 6 can be trialed without engaging themetaphyseal engagement feature 22 with the implanted stem. The teeth onthe distal surface 110 of the metaphyseal portion 6 can interface withthe implanted stem to provide stability, while the trial metaphysealportion 6 is locked together with the implanted stem. After determiningthe appropriate size for the metaphyseal portion, the definitivemetaphyseal portion can be joined with the implanted stem.

Although certain embodiments have been described herein for a trialhumeral implant, any of the components described herein can be used fora definitive humeral implant, or other trial or definitive implants forother anatomies such as femoral replacements or knee replacements.

Terminology

Certain embodiments have been described herein with a single spacer.However, any number of spacers can be used to form the humeral implant(e.g., two, three, four, or more). Further, the spacers in the humeralimplant do not need to be identical. For example, the spacers can havedifferent engagement features (e.g., threadable engagements, slidableengagements, etc.). As another example, the spacer may not include oneor more of the spring, the stopper, and the flange portion of the pin.

Certain methods are described as sliding a first component relative to asecond component. However, it should be understood that it is possibleto slide the second component relative to the first component. Forexample, “sliding the intermediate portion in a transverse directionrelative to a longitudinal axis of the metaphyseal portion” can alsoinclude “sliding the metaphyseal portion in a transverse directionrelative to a longitudinal axis of the intermediate portion.”

“Implant” is a broad term and is to be given its ordinary and customarymeaning to a person of ordinary skill in the art and includes, withoutlimitation, temporary implants (e.g., for trialing) or permanentimplants (also referred to herein as definitive implants) for anyanatomy, including, but not limited to, shoulder replacements, knewreplacements, femoral replacements, and hip replacements.

As used herein, the term “metaphyseal portion” refers to either areverse metaphyseal portion or an anatomic metaphyseal portion unlessotherwise specified.

As used herein, the relative terms “proximal” and “distal” shall bedefined from the perspective of the humeral component. Thus, proximalrefers to the direction of the metaphyseal portion and distal refers tothe direction of the stem portion.

For expository purposes, the term “transverse” as used herein is definedas a direction generally perpendicular to the longitudinal axis of theassembly, unless otherwise specified.

Conditional language, such as “can,” “could,” “might,” or “may,” unlessspecifically stated otherwise, or otherwise understood within thecontext as used, is generally intended to convey that certainembodiments include, while other embodiments do not include, certainfeatures, elements, and/or steps. Thus, such conditional language is notgenerally intended to imply that features, elements, and/or steps are inany way required for one or more embodiments.

The terms “comprising,” “including,” “having,” and the like aresynonymous and are used inclusively, in an open-ended fashion, and donot exclude additional elements, features, acts, operations, and soforth. Also, the term “or” is used in its inclusive sense (and not inits exclusive sense) so that when used, for example, to connect a listof elements, the term “or” means one, some, or all of the elements inthe list.

The terms “approximately,” “about,” “generally,” and “substantially” asused herein represent an amount close to the stated amount that stillperforms a desired function or achieves a desired result. For example,the terms “approximately,” “about,” “generally,” and “substantially” mayrefer to an amount that is within less than 10% of the stated amount, asthe context may dictate.

The ranges disclosed herein also encompass any and all overlap,sub-ranges, and combinations thereof. Language such as “up to,” “atleast,” “greater than,” “less than,” “between” and the like includes thenumber recited. Numbers preceded by a term such as “about” or“approximately” include the recited numbers. For example, “about four”includes “four”

Any methods disclosed herein need not be performed in the order recited.The methods disclosed herein include certain actions taken by apractitioner; however, they can also include any third-party instructionof those actions, either expressly or by implication. For example,actions such as “distally moving a locking element” include “instructingdistal movement of the locking element.”

Although certain embodiments and examples have been described herein, itwill be understood by those skilled in the art that many aspects of thehumeral assemblies shown and described in the present disclosure may bedifferently combined and/or modified to form still further embodimentsor acceptable examples. All such modifications and variations areintended to be included herein within the scope of this disclosure. Awide variety of designs and approaches are possible. No feature,structure, or step disclosed herein is essential or indispensable.

Some embodiments have been described in connection with the accompanyingdrawings. However, it should be understood that the figures are notdrawn to scale. Distances, angles, etc. are merely illustrative and donot necessarily bear an exact relationship to actual dimensions andlayout of the devices illustrated. Components can be added, removed,and/or rearranged. Further, the disclosure herein of any particularfeature, aspect, method, property, characteristic, quality, attribute,element, or the like in connection with various embodiments can be usedin all other embodiments set forth herein. Additionally, it will berecognized that any methods described herein may be practiced using anydevice suitable for performing the recited steps.

For purposes of this disclosure, certain aspects, advantages, and novelfeatures are described herein. It is to be understood that notnecessarily all such advantages may be achieved in accordance with anyparticular embodiment. Thus, for example, those skilled in the art willrecognize that the disclosure may be embodied or carried out in a mannerthat achieves one advantage or a group of advantages as taught hereinwithout necessarily achieving other advantages as may be taught orsuggested herein.

Moreover, while illustrative embodiments have been described herein, thescope of any and all embodiments having equivalent elements,modifications, omissions, combinations (e.g., of aspects across variousembodiments), adaptations and/or alterations as would be appreciated bythose in the art based on the present disclosure. The limitations in theclaims are to be interpreted broadly based on the language employed inthe claims and not limited to the examples described in the presentspecification or during the prosecution of the application, whichexamples are to be construed as non-exclusive. Further, the actions ofthe disclosed processes and methods may be modified in any manner,including by reordering actions and/or inserting additional actionsand/or deleting actions. It is intended, therefore, that thespecification and examples be considered as illustrative only, with atrue scope and spirit being indicated by the claims and their full scopeof equivalents.

Example Embodiments

The following example embodiments identify some possible permutations ofcombinations of features disclosed herein, although other permutationsof combinations of features are also possible.

1. A humeral implant trial assembly comprising:

-   -   a stem portion comprising a stem engagement feature;    -   a metaphyseal portion comprising a metaphyseal engagement        feature and a lumen extending longitudinally therethrough;    -   a locking element positioned in the metaphyseal lumen of the        metaphyseal portion; and    -   an intermediate portion comprising at least one spacer, each        spacer comprising:        -   a proximal engagement feature;        -   a distal engagement feature;        -   a lumen extending longitudinally through said spacer, the            lumen configured to be longitudinally aligned with the            metaphyseal lumen when the trial assembly is in a locked            configuration; and        -   a pin slidable within the lumen of said spacer;    -   wherein distal movement of the locking element translates the        pin of each spacer to secure the metaphyseal portion, the        intermediate portion, and the stem portion in the locked        configuration.

2. The trial assembly of Embodiment 1, wherein each of the proximalengagement feature and the distal engagement feature is a T-shaped slotor a T-shaped protrusion.

3. The trial assembly of Embodiment 1 or 2, wherein the intermediateportion is configured to engage the metaphyseal engagement featureand/or the stem engagement feature by sliding the intermediate portiontransverse to a longitudinal axis of the intermediate portion and intoengagement with the metaphyseal engagement feature and/or the stemengagement feature.

4. The trial assembly of Embodiment 3, wherein the intermediate portionis configured to unilaterally engage the metaphyseal engagement featureand/or the stem engagement feature only by sliding the intermediateportion in a single direction transverse to a longitudinal axis of theintermediate portion.

5. The trial assembly of any one of the preceding Embodiments, whereinat least a portion of the lumen in the metaphyseal portion is threaded.

6. The trial assembly of any one of the preceding Embodiments, whereinthe pin further comprises a flange portion, the flange portionconfigured to limit proximal and/or distal movement of the pin.

7. The trial assembly of any one of the preceding Embodiments, eachspacer further comprises a stopper in the lumen of said spacer, thestopper configured to limit distal movement of the pin.

8. The trial assembly of any one of the preceding Embodiments, furthercomprising a spring positioned in the lumen of each spacer.

9. The trial assembly of Embodiment 8, wherein the spring is configuredto bias the pin in a proximal direction.

10. The trial assembly of any one of the preceding Embodiments, whereinthe stem portion further comprises a recess configured to receive thepin of one of said at least one spacer, the stem portion furthercomprising a channel extending from an outer surface of the stem portionto a distal end of the recess, the channel configured to receive anelongate structure to move the pin proximally and release the trialassembly from the locked configuration.

11. The trial assembly of any one of the preceding Embodiments, whereinthe intermediate portion comprises a plurality of spacers.

12. The trial assembly of Embodiment 11, wherein each spacer isconfigured to engage an adjacent spacer by sliding said spacertransverse to a longitudinal axis of said spacer and into engagementwith the adjacent spacer.

13. A spacer for use in a medical implant, the spacer comprising:

-   -   a body portion, the body portion comprising a first engagement        feature and a second engagement feature, each of the first        engagement feature and the second engagement feature configured        to engage other components of the medical implant;    -   a lumen extending longitudinally through the body portion;    -   a pin slidable through the lumen of the body portion, at least a        distal portion of the pin comprising a smooth outer surface, the        pin comprising a flange portion configured to limit proximal        and/or distal movement of the pin; and    -   a spring positioned radially between the pin and the body        portion.

14. The spacer of Embodiment 13, wherein the medical implant is selectedfrom the group consisting of a humeral implant and a femoral implant.

15. The spacer of Embodiment 13 or 14, wherein the medical implant is atrial implant.

16. A method of locking a trial humeral implant, the method comprising:

-   -   assembling a metaphyseal portion, an intermediate portion, and a        stem portion, the assembling comprising:        -   sliding the intermediate portion into engagement with            metaphyseal portion;        -   sliding the stem portion into engagement with intermediate            portion, the intermediate portion comprising at least one            spacer, each spacer comprising:            -   a proximal engagement feature;            -   a distal engagement feature;            -   a lumen extending longitudinally through said spacer;                and            -   a pin slidable within the lumen of said spacer;    -   locking the trial humeral implant by distally moving a locking        element disposed in the metaphyseal portion to translate the pin        of each spacer to secure the metaphyseal portion, the        intermediate portion, and the stem portion into a locked        configuration; and    -   implanting the humeral implant in the locked configuration.

17. The method of Embodiment 16, wherein the intermediate portioncomprises a plurality of spacers.

18. The method of Embodiment 27, further comprising assembling theintermediate portion by sliding each spacer transverse to a longitudinalaxis of an adjacent spacer and into engagement with the adjacent spacer.

19. The method of any one of Embodiments 16 to 18, further comprisingmoving the locking element in a proximal direction to release thehumeral implant from the locked configuration.

The following is claimed:
 1. A humeral implant trial assemblycomprising: a stem portion comprising a stem engagement feature; ametaphyseal portion comprising a metaphyseal engagement feature and alumen extending longitudinally therethrough; a locking elementpositioned in the metaphyseal lumen of the metaphyseal portion; and anintermediate portion comprising at least one spacer, each spacercomprising: a proximal engagement feature; a distal engagement feature;a lumen extending longitudinally through said spacer, the lumenconfigured to be longitudinally aligned with the metaphyseal lumen whenthe trial assembly is in a locked configuration; and a pin slidablewithin the lumen of said spacer; wherein distal movement of the lockingelement translates the pin of each spacer to secure the metaphysealportion, the intermediate portion, and the stem portion in the lockedconfiguration.
 2. The trial assembly of claim 1, wherein each of theproximal engagement feature and the distal engagement feature is aT-shaped slot or a T-shaped protrusion.
 3. The trial assembly of claim1, wherein the intermediate portion is configured to engage themetaphyseal engagement feature and/or the stem engagement feature bysliding the intermediate portion transverse to a longitudinal axis ofthe intermediate portion and into engagement with the metaphysealengagement feature and/or the stem engagement feature.
 4. The trialassembly of claim 3, wherein the intermediate portion is configured tounilaterally engage the metaphyseal engagement feature and/or the stemengagement feature by sliding the intermediate portion in a singledirection transverse to a longitudinal axis of the intermediate portion.5. The trial assembly of claim 1, wherein at least a portion of thelumen in the metaphyseal portion is threaded.
 6. The trial assembly ofclaim 1, wherein the pin further comprises a flange portion, the flangeportion configured to limit proximal and/or distal movement of the pin.7. The trial assembly of claim 1, wherein each spacer further comprisesa stopper in the lumen of said spacer, the stopper configured to limitdistal movement of the pin.
 8. The trial assembly of claim 1, furthercomprising a spring positioned in the lumen of each spacer.
 9. The trialassembly of claim 8, wherein the spring is configured to bias the pin ina proximal direction.
 10. The trial assembly of claim 1, wherein thestem portion further comprises a recess configured to receive the pin ofone of said at least one spacer, the stem portion further comprising achannel extending from an outer surface of the stem portion to a distalend of the recess, the channel configured to receive an elongatestructure to move the pin proximally and release the trial assembly fromthe locked configuration.
 11. The trial assembly of claim 1, wherein theintermediate portion comprises a plurality of spacers.
 12. The trialassembly of claim 11, wherein each spacer is configured to engage anadjacent spacer by sliding said spacer transverse to a longitudinal axisof said spacer and into engagement with the adjacent spacer.
 13. Aspacer for use in a medical implant, the spacer comprising: a bodyportion, the body portion comprising a first engagement feature and asecond engagement feature, each of the first engagement feature and thesecond engagement feature configured to engage other components of themedical implant; a lumen extending longitudinally through the bodyportion; a pin slidable through the lumen of the body portion, at leasta distal portion of the pin comprising a smooth outer surface, the pincomprising a flange portion configured to limit proximal and/or distalmovement of the pin; and a spring positioned radially between the pinand the body portion wherein the medical implant is a humeral implant.14. A method of locking a trial humeral implant, the method comprising:assembling a metaphyseal portion, an intermediate portion, and a stemportion, the assembling comprising: sliding the intermediate portioninto engagement with metaphyseal portion; sliding the stem portion intoengagement with intermediate portion, the intermediate portioncomprising at least one spacer, each spacer comprising: a proximalengagement feature; a distal engagement feature; a lumen extendinglongitudinally through said spacer; and a pin slidable within the lumenof said spacer; locking the trial humeral implant by distally moving alocking element disposed in the metaphyseal portion to translate the pinof each spacer to secure the metaphyseal portion, the intermediateportion, and the stem portion into a locked configuration; andimplanting the humeral implant in the locked configuration.
 15. Themethod of claim 14, wherein the intermediate portion comprises aplurality of spacers.
 16. The method of claim 15, further comprisingassembling the intermediate portion by sliding each spacer transverse toa longitudinal axis of an adjacent spacer and into engagement with theadjacent spacer.
 17. The method of claim 14, further comprising movingthe locking element in a proximal direction to release the humeralimplant from the locked configuration.
 18. A spacer for use in a medicalimplant, the spacer comprising: a body portion, the body portioncomprising a first engagement feature and a second engagement feature,each of the first engagement feature and the second engagement featureconfigured to engage other components of the medical implant; a lumenextending longitudinally through the body portion; a pin slidablethrough the lumen of the body portion, at least a distal portion of thepin comprising a smooth outer surface, the pin comprising a flangeportion configured to limit proximal and/or distal movement of the pin;and a spring positioned radially between the pin and the body portion,wherein the medical implant is a femoral implant.